1. Field of the Invention
This invention relates to a method and apparatus for preparing a distal surface of a human femur. More particularly, it relates to a set of instruments and a method for their use to prepare the surface of the femur to receive a distal femoral prosthesis.
2. Description of the Prior Art
Various types of instruments and methods have been developed to enable a surgeon to affix a distal femoral knee prosthesis to a human femur. Since the purpose for affixing such a prosthesis is to restore the patient's ability to walk after disease or other traumatic causes have impaired that ability, it is important that the prosthesis be attached to the femur in a manner that will approximate as closely as possible the natural condyles which the prosthesis is replacing.
It is a common practice to use the long central axis of the femur as a guide in determining the manner in which the distal femoral surfaces should be shaped to receive a properly aligned distal femoral prosthesis. Using the long central axis of the femur as a guide, a planar distal cut is first made on the distal femur and then the guide is removed and additional instrumentation utilizes the planar distal surface as a reference from which to cut anterior and posterior cuts, followed by anterior and posterior chamfer cuts.
Patents showing such a method or methods similar thereto are U.S. Pat. Nos. 4,474,177 and 4,721,104. The former patent relates to a series of instruments for preparing the distal femur in which an angled alignment guide is used to index a plateau planar which is used to prepare the planar distal surface of the femur. The latter patent relates to a surgical apparatus for preparing the intracondylar area of the distal femur.
U.S. Pat. No. 5,047,032 relates to a surgical instrument designed to produce a planar distal femoral surface. A router or side cutting drill is used to form the surface. Another patent which relates to the preparation of the distal femur is U.S. Pat. No. 4,787,383, in which a saw is used to make the planar femoral cut. A saw guide is also disclosed.